idea.... solar yard lamps!

Few weeks ago, my mother got a couple of new yard lamps. LED, super bright, and they run just about all night. It might have been this guy:

http://www.hardwareandtools.com/invt/5103551?ref=gbase

If not, pretty much identical. Walmart and HOme Depot both have them for $20.

My thought is... the solar panel and battery charger are on the pallet above the lamp. It looks easy enough to pull that off and use it stand alone, maybe epoxy a MALICE clip to the back to attach it to packs. Then leave terminals where the wires are, so I can clip leads to the lamp if I chose to use it at night. It runs on four ni-cad AAs. I'm thinking should be easy enough to isolate the day/night sensor, and maybe add a switch if I really want one. Or turn the whole thing into a strobe with the addition of something the size of a AA (cap, maybe a couple of resistors) that you can choose to add. Or just a multi position switch....

But the lamp itself isn't very big. Another clip would let you mount it over the shoulder (ala Aliens) or to a bike or to almost any surface. And I'm pretty sure if you had to, the lamp and charger would survive being powered with some alkalines. It is already water proof, and it is LIGHT for what it is, less than a pound. Of course, with this on clip leads, the charger can be a stand alone item.

Never seen a circuit diagram for one of these things. Does anyone have a clue what kind of sensor they are using? Any surprises I should be wondering about?

Am I crazy, or just crazy enough for this to work?

I say have at it and report back what you find! Backpackable solar power would have a lot of uses. There's plenty of systems already available, but when you build it yourself you get a lot more options.

-Blast

Hi Ironraven,

The circuit will probably be a really simple one such as shown below, using an Light Dependant Resistor (LDR), a single transistor or darlington, a few resistors (the 470 ohm resistor and LED is replaced with something like a 3 x 47 ohm resistors and 3 LEDs), a variable preset resistor (to set the light value to switch on the LEDs) and the LEDs (shows a single LED in the circuit). The voltage from the NiMh or NiCd cells will probably be unregulated. I would assume about 3.6 v (+Vs) as the garden lamp has 3 NiMh cells stacked in series. The Solar Cell will most likely be something like a 4-4.5 Volt 120-140mA Solar Cell (depending on the solar cell Area) such as here at http://www.dealextreme.com/details.dx/sku.12391 with a reverse blocking diode at around 0.6V to give the 3.6-4.0V for the NiMh cells. Total Solar power will be around 0.45 Watts assumming the solar cell is this large 8cm by 8cm (the one on the garden light looks to be a lot smaller possibly half the power). The NiMh cells are most likely to be generic 1.2v 600 mAHr AAA cells. Charge time for the cells will be around 6 to 8 hrs in bright sunlight (double this for the smaller solar cell on the garden light).




The LEDs will have a typical power output around 60 mW each giving a total of 180 mW output. Total power for the circuit would be around 0.4 - 0.5 Watts giving roughly about 4-6 hrs lighting use. Efficiency is poor for this type of circuit but the component costs are very small.

Deal Extreme has lots of different Solar Cell Chargers such as this one at http://www.dealextreme.com/details.dx/sku.4813 being much more flexible in use. With this device you could connect one of these USB LED lights http://www.dealextreme.com/details.dx/sku.5452 and still power another USB device such a MP3 player or Cell Phone at the same time.

For less than $20 even something like this at http://www.dealextreme.com/details.dx/sku.9134 will produce more solar power. A video is also available showing the solar charger here at http://www.youtube.com/watch?v=sl7lgFhNTs8

Hope this helps.

I've used solar-powered yard lights at Burning Man for years, and they are not the most robust items I've seen. I don't know about the ones you are considering, but the ones I have don't last more then a few years (out for one week on the playa, so that's a few weeks' use).

Here are photos of one I took apart:
http://civex.smugmug.com/gallery/5099462_pLNsB

Two AA batteries, one LED, a circuit board, and the solar panel. Yours will vary, but it shouldn't be too difficult to dismantle then re-assemble more or less as you wish. I would give it a good testing period before relying on it. It's water proof now, it stays on all night now, etc. Burning Man is a harsh environment, so I may be too hard on them, but I would be interested in seeing how long the units stay working at the claimed specs.

This is a really good link describing garden solar light electronics;

http://www.talkingelectronics.com/projects/SolarLight/SolarLight.html

The electronics may be slightly more sophisticated than originally thought.

About 2 years ago, in October, we had an earthquake and lost power state wide. My co-worker's father took several of these LED yard lamps and removed the bottom halves off. He then brought them into the house to light up the kitchen and living room. It was a great idea.

Ironraven, I you should try experimenting and let us know.

http://www.reuk.co.uk/Solar-Battery-Charging.htm

DIY solar battery charger

http://www.instructables.com/id/Solar-Battery-Charging/

http://www.instructables.com/id/Rain-or-Shine-Solar-Charger/

http://www.instructables.com/id/Universal-Solar-Charger/

whole bunch of solar projects there

Why use a diagram which uses the European symbol for resistor rather then the American symbol for resistor? Wouldn't more people recognize the American standard?

Jeanette Isabelle

I like the idea of using solar yard lights as a component in my home based E-kit ... but with a switchable light ...so I could turn it off if desired.
Though it would be nice if they were robust enough to get bumped around a bit and definitley long lasting enough for the whole night ....so I could use them for outside security etc. ONce the big quale hits here in Cali ... power might be out more than one night.
Great link to the dealextreme website for that pocket solar charger ... that might prove real handy to have around !
Thanks for feeding my gadget habit !
And of course, it looks like it might be better to fab up my own for a more portable and compact setup for for mobile bugging out....or just camping out in general.

Bah, buying it is less fun. And this gives me a work lamp of reasonable impressiveness that I can clip to it. :P

And thanks for the schematics, I hadn't found anything on what they were using for a sensor.

*whispers* Jeanette, he's English,

british please

Seems easy enough to read, all resistors are marked with the values as is the pot.

It is easy to read, I did not understand why the American standard wasn't used. Iron Raven explained it to me.

Jeanette Isabelle

I found a floating pool light on discount that I snapped up for the quality panel that was in it, haven't built anything out of it because I already have the solar gadgets I need. The plan was to buy a second car charger for my cell phone and cut the tip off and wire it "directly" to the panel (adding any resistors and whatever) to make a pocket size phone charger.

Since I already have two solar panels and one or more dynamo gadgets able to charge the phone the frugal side of me won't spend the money, but good luck to you, and let us know what works out.

C'mon! Consider yourself drawing the American resistor sign in MS Word or Paintbrush with only your mouse... Note then, how much time it took (1-5 min) and divide that by how neat and professional your resistor looks on a diagram (1 to 5), that's the amount of frustration you get...

[rant on]
American standard... Its roots are in the Imperial standard, which purpose was to complicate things so much that they are less accessible for the poor people, I believe. I.o.w., who can't pay for higher education or/and for a pair of compasses.
[rant off]

Back on topic. I'd get some PowerFilm scraps instead (I did already actually). Much more powerful than what could be found on any garden lights. Much smaller, lighter, shatterproof, waterproof. The current required to light a diode is nothing compared to what a Li-Ion battery needs to replentish its juice.

Why would anyone draw a schematic using MS Word?

Jeanette Isabelle

Because usually people have at least MSOffice Basic available on their computers preinstalled. And that's usually the only vector graphics editor readily available for quick schematics drafting (suitable enough for sharing ideas on forums for example). OrCAD would be overkill for that.

For quick schematic sketches, I suggest the free ExpressSCH software. Its meant to be used with the free PCB layout software which is meant to be used to order quick turn PCBs.

The catch is that the format only works with their service, it is only really suited for the hobbyist. I use Eagle serious stuff but I still use ExpressSCH for quick sketches.

Back on topic, I suspect they use a CdS cell for the light sensor. The circuit shown by AFLM will work buy the LED will come on gradually as the ambient light dims. I would use a comparator with hysteresis so that it snaps on at some point. Actually, I'd use a little microcontroller that sleeps for most of the time and just wakes up to check the light level once in a while.

But that's just me.

Granted, not everyone has a CAD program installed on their computer. On the other hand, not everyone is able to read schematics, not to mention draw them.


A CAD program is the right tool for the job.

Jeanette Isabelle

If that's your job - I'd agree somewhat. Otherwise it will look like hammering a nail with a microscope. And the "right tool for the job" in this context sounds like Home Depot commercial ad slogan to me.

I don't understand your metaphor. Why not draw schematics with a program designed for drawing schematics?

Jeanette Isabelle

That's solely from my experience . I was teaching students to render professional video clips in Adobe Premiere, somewhere 10 years ago (I have the license and disks somewhere on the shelves). I'm (Ok, I was) proficient with my "Microscope". But that's not my job anymore. So, when I need to send a DVD to my family with my home video project (to "hammer a nail"), I'd rather start up a dummy proof simplistic video editing utility, which came with my digital camera, than go through Premiere installation and setup, recall the sequence of operation, all the tricks and quirks of it, plan the production release schedule, and e.t.c. Because I know that I wouldn't need a 1% of Premiere functionality for this little job, so I'd rather spend more time improvising my movie plot to be more fun and less boring .

Seriously, are you trolling?



Population of America (USA): 300 million
Population of Europe (EU): 500 million

So, er, no.



Because they didn't have a napkin?

You are right, however, that a CAD program would be the right tool for the job. I recommend KiCAD. It's open source, cross-platform, and free.

Furthermore (and actually on topic), the solar garden lights can generate a lot of good and interesting ideas. I have read of a project that uses a step-up converter (a MAXIM chip) to power a weather station at 5V from a solar-lamp-based supply (1.2V), thus freeing it from wires. It had a wireless module to send its weather data periodically. Someone else had mounted the top panels from a number of lamps on their roof, and then ran small wires from the roof to the LEDs in the ceiling of the floor below, so that the rooms and hallways were always lit with a low background level of light. I myself did a simple hack for my mailbox: I pulled the top part off the lamp and soldered longer wires onto the LED. I mounted the top panel onto the top of my mailbox, and mounted the LED so it would shine on my house number on the front of the mailbox to make it more visible at night.

A

Excuse me. That was uncalled for. I posted a valid question.

Jeanette Isabelle

I keep solar yard lamps in the back yard which keeps them from being stolen.

If power goes out, I take the light diffuser from the lamp, turn it upside down on the tabe and we will have enough light to play cards with. They also make great night lights in the bathrooms and in the kids' bedrooms.